Commit message: Fix UAF in aaaa on arm/thumb switching ##crash

* Reported by @peacock-doris via huntr.dev
* Reproducer tests_65185
* This is a logic fix, but not the fully safe as changes in the code
  can result on UAF again, to properly protect r2 from crashing we
  need to break the ABI and add refcounting to RRegItem, which can't
  happen in 5.6.x because of abi-compat rules
CVE: CVE-2022-1031
CWE: CWE-416
Vulnerability description: Use After Free in op_is_set_bp in GitHub repository radareorg/radare2 prior to 5.6.6.

Project: radare2

static void extract_arg(RAnal *anal, RAnalFunction *fcn, RAnalOp *op, const char *reg, const char *sign, char type) {
	st64 ptr = 0;
	char *addr, *esil_buf = NULL;
	const st64 maxstackframe = 1024 * 8; 

	r_return_if_fail (anal && fcn && op && reg);

	size_t i;
	for (i = 0; i < R_ARRAY_SIZE (op->src); i++) {
		if (op->src[i] && op->src[i]->reg && op->src[i]->reg->name) {
			if (!strcmp (reg, op->src[i]->reg->name)) {
				st64 delta = op->src[i]->delta;
				if ((delta > 0 && *sign == '+') || (delta < 0 && *sign == '-')) {
					ptr = R_ABS (op->src[i]->delta);
					break;
				}
			}
		}
	}

	if (!ptr) {
		const char *op_esil = r_strbuf_get (&op->esil);
		if (!op_esil) {
			return;
		}
		esil_buf = strdup (op_esil);
		if (!esil_buf) {
			return;
		}
		r_strf_var (esilexpr, 64, ",%s,%s,", reg, sign);
		char *ptr_end = strstr (esil_buf, esilexpr);
		if (!ptr_end) {
			free (esil_buf);
			return;
		}
		*ptr_end = 0;
		addr = ptr_end;
		while ((addr[0] != '0' || addr[1] != 'x') && addr >= esil_buf + 1 && *addr != ',') {
			addr--;
		}
		if (strncmp (addr, "0x", 2)) {
			//XXX: This is a workaround for inconsistent esil
			if (!op->stackop && op->dst) {
				const char *sp = r_reg_get_name (anal->reg, R_REG_NAME_SP);
				const char *bp = r_reg_get_name (anal->reg, R_REG_NAME_BP);
				const char *rn = op->dst->reg ? op->dst->reg->name : NULL;
				if (rn && ((bp && !strcmp (bp, rn)) || (sp && !strcmp (sp, rn)))) {
					if (anal->verbose) {
						eprintf ("Warning: Analysis didn't fill op->stackop for instruction that alters stack at 0x%" PFMT64x ".\n", op->addr);
					}
					goto beach;
				}
			}
			if (*addr == ',') {
				addr++;
			}
			if (!op->stackop && op->type != R_ANAL_OP_TYPE_PUSH && op->type != R_ANAL_OP_TYPE_POP
				&& op->type != R_ANAL_OP_TYPE_RET && r_str_isnumber (addr)) {
				ptr = (st64)r_num_get (NULL, addr);
				if (ptr && op->src[0] && ptr == op->src[0]->imm) {
					goto beach;
				}
			} else if ((op->stackop == R_ANAL_STACK_SET) || (op->stackop == R_ANAL_STACK_GET)) {
				if (op->ptr % 4) {
					goto beach;
				}
				ptr = R_ABS (op->ptr);
			} else {
				goto beach;
			}
		} else {
			ptr = (st64)r_num_get (NULL, addr);
		}
	}

	if (anal->verbose && (!op->src[0] || !op->dst)) {
		eprintf ("Warning: Analysis didn't fill op->src/dst at 0x%" PFMT64x ".\n", op->addr);
	}

	int rw = (op->direction == R_ANAL_OP_DIR_WRITE) ? R_ANAL_VAR_ACCESS_TYPE_WRITE : R_ANAL_VAR_ACCESS_TYPE_READ;
	if (*sign == '+') {
		const bool isarg = type == R_ANAL_VAR_KIND_SPV ? ptr >= fcn->stack : ptr >= fcn->bp_off;
		const char *pfx = isarg ? ARGPREFIX : VARPREFIX;
		st64 frame_off;
		if (type == R_ANAL_VAR_KIND_SPV) {
			frame_off = ptr - fcn->stack;
		} else {
			frame_off = ptr - fcn->bp_off;
		}
		if (maxstackframe != 0 && (frame_off > maxstackframe || frame_off < -maxstackframe)) {
			goto beach;
		}
		RAnalVar *var = get_stack_var (fcn, frame_off);
		if (var) {
			r_anal_var_set_access (var, reg, op->addr, rw, ptr);
			goto beach;
		}
		char *varname = NULL, *vartype = NULL;
		if (isarg) {
			const char *place = fcn->cc ? r_anal_cc_arg (anal, fcn->cc, ST32_MAX) : NULL;
			bool stack_rev = place ? !strcmp (place, "stack_rev") : false;
			char *fname = r_type_func_guess (anal->sdb_types, fcn->name);
			if (fname) {
				ut64 sum_sz = 0;
				size_t from, to, i;
				if (stack_rev) {
					const size_t cnt = r_type_func_args_count (anal->sdb_types, fname);
					from = cnt ? cnt - 1 : cnt;
					to = fcn->cc ? r_anal_cc_max_arg (anal, fcn->cc) : 0;
				} else {
					from = fcn->cc ? r_anal_cc_max_arg (anal, fcn->cc) : 0;
					to = r_type_func_args_count (anal->sdb_types, fname);
				}
				const int bytes = (fcn->bits ? fcn->bits : anal->bits) / 8;
				for (i = from; stack_rev ? i >= to : i < to; stack_rev ? i-- : i++) {
					char *tp = r_type_func_args_type (anal->sdb_types, fname, i);
					if (!tp) {
						break;
					}
					if (sum_sz == frame_off) {
						vartype = tp;
						varname = strdup (r_type_func_args_name (anal->sdb_types, fname, i));
						break;
					}
					ut64 bit_sz = r_type_get_bitsize (anal->sdb_types, tp);
					sum_sz += bit_sz ? bit_sz / 8 : bytes;
					sum_sz = R_ROUND (sum_sz, bytes);
					free (tp);
				}
				free (fname);
			}
		}
		if (!varname) {
			if (anal->opt.varname_stack) {
				varname = r_str_newf ("%s_%" PFMT64x "h", pfx, R_ABS (frame_off));
			} else {
				varname = r_anal_function_autoname_var (fcn, type, pfx, ptr);
			}
		}
		if (varname) {
#if 0
			if (isarg && frame_off > 48) {
				free (varname);
				goto beach;
			}
#endif
			RAnalVar *var = r_anal_function_set_var (fcn, frame_off, type, vartype, anal->bits / 8, isarg, varname);
			if (var) {
				r_anal_var_set_access (var, reg, op->addr, rw, ptr);
			}
			free (varname);
		}
		free (vartype);
	} else {
		st64 frame_off = -(ptr + fcn->bp_off);
		if (maxstackframe != 0 && (frame_off > maxstackframe || frame_off < -maxstackframe)) {
			goto beach;
		}
		RAnalVar *var = get_stack_var (fcn, frame_off);
		if (var) {
			r_anal_var_set_access (var, reg, op->addr, rw, -ptr);
			goto beach;
		}
		char *varname = anal->opt.varname_stack
			? r_str_newf ("%s_%" PFMT64x "h", VARPREFIX, R_ABS (frame_off))
			: r_anal_function_autoname_var (fcn, type, VARPREFIX, -ptr);
		if (varname) {
			RAnalVar *var = r_anal_function_set_var (fcn, frame_off, type, NULL, anal->bits / 8, false, varname);
			if (var) {
				r_anal_var_set_access (var, reg, op->addr, rw, -ptr);
			}
			free (varname);
		}
	}
beach:
	free (esil_buf);
}